The present invention generally relates to implantable stimulation devices and methods and systems for treating patients with congestive heart failure (CHF).
Congestive heart failure (CHF) is defined generally as the inability of the heart to deliver enough blood to the peripheral tissues to meet metabolic demands. Frequently, CHF is manifested by left heart dysfunction, but it can have a variety of sources. For example, CHF patients may have any one of several different conduction defects. The natural electrical activation system through the heart involves sequential events starting with the sino-atrial (SA) node, and continuing through the atrial conduction pathways of Bachmann""s bundle and internodal tracts at the atrial level, followed by the atrio-ventricular (AV) node, Common Bundle of His, right and left bundle branches, and final distribution to the distal myocardial terminals via the Purkinje fiber network. A common type of intra-atrial conduction defect is known as intra-atrial blockxe2x80x94a condition where the atrial activation is delayed in getting from the right atrium to the left atrium. In left bundle branch block and right bundle branch block, the activation signals are not conducted in a normal fashion along the right or left bundle branches respectively. Thus, in a patient with bundle branch block, the activation of the ventricle is slowed, and the QRS is seen to widen due to the increased time for the activation to traverse the conduction path.
CHF manifested by such conduction defects and/or other cardiomyopathies are the object of considerable research into treatments for improving cardiac output. In a healthy heart, cardiac output is typically not a problem. In patients with CHF, cardiac output is typically a problem. Because an unhealthy heart does not function properly insofar as important timing issues are concerned (e.g. A-V timing and V-V timing), cardiac output can be adversely affected. Hence, there is a continuing need to address timing issues in CHF patients. More specifically, there is a continuing need to provide improved cardiac output for CHF patients.
Accordingly, this invention arose out of concerns associated with providing improved methods and systems for determining desirable or optimal timing parameters for pacing CHF patients.
Various embodiments provide techniques and systems that can ensure that patients with congestive heart failure receive pacing therapy that optimizes their hemodynamic performance in view of various variables that pertain to the patient. Exemplary variables can include, without limitation, the time of day, patient posture and activity level.
The following description is of the best mode presently contemplated for practicing the invention. This description is not to be taken in a limiting sense but is made merely for the purpose of describing the general principles of the invention. The scope of the invention should be ascertained with reference to the issued claims.
FIG. 1 is a simplified diagram illustrating an implantable stimulation device in electrical communication with at least three leads implanted into a patient""s heart for delivering multi-chamber stimulation and shock therapy.
FIG. 2 is a functional block diagram of a multi-chamber implantable stimulation device illustrating exemplary basic elements of a stimulation device which can provide cardioversion, defibrillation and/or pacing stimulation in up to four chambers of the heart.
FIG. 3 is a flow diagram that describes steps in a method in accordance with one embodiment.
FIG. 4 is a graph that is useful in understanding various inventive embodiments.
FIG. 5 illustrates a three dimensional surface that can be constructed in accordance with one or more described embodiments.
FIG. 6 is a flow diagram that describes steps in a method in accordance with one embodiment.
FIG. 7 is a graph that is useful in understanding various inventive embodiments.